This is a tough area. If you go look at various types of infrastructure providers (e.g. EC2, Linode, Rackspace) you'll see that they always end up making up vague units of measurement (e.g. "cores") and then showing all the resources in reference to whatever the base unit is. So there's really no good way to talk about CPU power like there is with memory.

That said, I can say that a 1X dyno is not very powerful compared to, say, any server you'd purchase for your own datacenter. Our intention is that 2X dynos will provide twice the CPU horsepower, although CPU and I/O are harder to allocate reliability in virtualized environments.